Irrigation Can Result in the Salinization of Soils Because

Selected farmlands in southern Baja California, Mexico, were surveyed to decide the levels and the causes of salinization/sodication in irrigated agricultural soil. The salt dynamics observed in profiles differed from farm to subcontract. Depression EC and high pH levels were observed in the profiles of sandy fields, because the salt composition of these soils tin easily modify when salts are leached by irrigation water that contains carbonates of sodium. On the other hand, high levels of salinity and sodicity were observed in the soils of clayey fields. Soil salinization/sodication is complexly interrelated with soil characteristics, the amount and composition of salts in the soil, the quantity and quality of irrigation h2o applied, and the irrigation methods used. Our findings bespeak that irrigation h2o in Baja California should be supplied at a rate that is sufficient to meet crop requirements without exacerbating salt accumulation.

1. Introduction

In arid regions, desertification is mainly acquired by human activity [i, ii]. Attempts to grow crops in arid inadequate irrigated areas have mainly resulted in the salinization and/or sodication of the soil. Because the irrigation of agricultural lands in barren regions has not however become a widespread practices a relatively small area has been degraded compared to the areas used for grazing or those in which rain-fed agronomics is carried out. Withal, irrigation tends to increase productivity in the curt term, and the need to produce food for an increasing population might result in the conversion of grazed, rain-fed, and even virgin lands to irrigated fields [three]. Furthermore, the reclamation of common salt-affected land that has been irrigated for agronomical purposes has go increasingly important. Reducing the severity and extent of soil salinity is primarily a matter of soil and water management. Practiced h2o management involves both preventing water received in the recharge areas from percolating into groundwater and maintaining the water tabular array of the discharge areas at low, condom levels. The well-nigh common arroyo to salinity direction is to maintain a prescribed leaching requirement. Nonetheless, this arroyo is ineffective when the irrigation water contains significant levels of sodium, carbonates, and bicarbonates. In addition, the surface drainage chapters of these barren soils is commonly poor.

The Baja California peninsula was one time a part of the North American Plate, of which mainland Mexico remains a office. In southern Baja California, Pliocene to early Quaternary sedimentary formations were deposited syntectonically over a major detachment that is associated with the exhumation of Mesozoic chaff [4]. The area has a very dry climate with an boilerplate annual rainfall that ranges from less than 100 to 300 mm. Mean temperatures typically range betwixt 18 to 22°C. Rainfall is characterized by its irregularity and variability in both time and infinite [5]. Though well-nigh soils in Baja California are low in organic matter, their levels of establish nutrients (except nitrogen) tend to be high. If sufficient irrigation h2o is available and temperatures are favourable, these soils tin exist fabricated highly productive for agriculture. The crops that are most profitable and best adapted to the atmospheric condition of the region are grown in La Paz due to economic force per unit area. These factors result in the cultivation of extensive monocultures, mainly of chilli peppers, frijol beans, and tomatoes. Legume crops are cultivated extensively in the southern role of the peninsula though the number of species that are adapted to the surface area is limited. The widespread utilise of commercial fertilizer has led to the contempo intensification of agronomics in localised areas of Baja California. In some areas, the indiscriminate apply of large amounts of chemical fertilizers and the overexploitation of groundwater has dramatically increased the amount of surface soils affected past salinity. Ingather cultivation redistributes water within a mural by changing the vegetative composition, the amount of water infiltration into the soil, and the amount of runoff, which can in turn beal the natural processes of soil salinization.

This report represents the starting time attempt to scientifically investigate the salinity of agricultural soils in southern Baja California. Nosotros hope to provide baseline data against which to compare futurity measurements of soil salinity and sodicity. The aims of the study were to (1) clarify the physicochemical backdrop of the soil, (2) evaluate the current state and severity of soil salinity and soil sodicity, and (three) appraise the probability of soil salinity levels increasing under the current agricultural land use and management practices. This study was carried out on selected small- and medium-calibration farmlands in southern Baja California, where at that place is piddling use of subterranean water for irrigation. The physicochemical properties of the cultivated soils were investigated to clarify the profile of salt distribution at the few sites where soils are irrigated. We besides evaluated the mechanisms of soil salinization and sodication in soils that are irrigated for agricultural purposes. Finally, the corporeality of available micronutrients present in the soil was assessed to determine the land's potential for agriculture.

2. Materials and Methods

2.1. Site Descriptions and Sampling Sites

The investigated expanse was El Carrizal in the suburbs of La Paz, southern Baja California, Mexico (Figure i). The average annual precipitation is less than 200 mm and the rainfall varies in time and space (Table ane). Both the tropical climate and the location of Baja California in the direct path of Pacific hurricanes ensure that the area receives more than tropical cyclones than any other role of Mexico. The rainy season extends from May to October, and most tropical cyclone impacts occur in September. This coincides with the statistical peak of the eastern North Pacific hurricane season, which occurs in belatedly August or early September. The area is characterized as dry, warm, and sunny with a mean annual temperature of 23°C–25°C.

	Jan.	Feb.	Mar.	Apr.	May	Jun.	Jul.	Aug.	Sep.	Oct.	Nov.	Dec.
Temperature (°C)	eighteen.0	19.4	20.4	22.half dozen	24.seven	27.4	29.eight	29.7	28.7	25.half dozen	22.i	nineteen.3
Rainfall (mm)	8	24	0	0	i	6	13	31	33	15	15	25

Five farmlands in the village of El Carrizal, where subterranean water is used for irrigation, were selected to assess the status of soil salinization equally report sites. Irrigation water was sampled from each farm. At that place is picayune use of underground h2o for irrigation in the investigated expanse. These farms located between 23°45′ to 23°47′ N and 110°16′ to 110°18′ W were used to stand for small- and medium-scale agronomics plots (Figure 1).

Site 1 has been in production for two years. The soil backdrop earlier and after cultivation of frijol beans were investigated at this site. Irrigation h2o was by and large applied for three hours every 3 days past drip irrigation. Site 2 has been in production for two years. Republic of chile guerito was the main crop here. Irrigation water was more often than not applied three hours every three days by baste irrigation. Site 3 has been farmed for a decade, primarily for the cultivation of Republic of chile guerito. Irrigation water was more often than not practical for half a day 3 days per week by drip irrigation. The soil of Sites 1, 2 and 3 were classified as typic torriorthents and aridic arenosols, according to soil taxonomy [6] and WRB nomenclature [7], respectively. Site 4 has been managed for virtually twenty yeas every ten to fifteen days by driprs, primarily for the tillage of Republic of chile guerito and frijol beans. Irrigation water was practical hither for 3-60 minutes irrigation. Site five has been managed for a decade, primarily for the culture of frijol bean. Irrigation water was generally applied for five hours every five to 6 days past drip irrigation. The soil of Sites 4 and 5 were classified as petroargids and sodic solonchaks, according to soil taxonomy [6] and WRB nomenclature [7], respectively. Sites 4 and 5 drew their irrigation water from the aforementioned well. The other sites used its own well.

2.2. Analysis of Soil and Irrigation Water

Geostatistics can be defined as a set of tools and techniques to analyze spatial patterns and predict the values of a continuous variable distributed in space or in time at unsampled locations [viii–xi]. During November 2002 (before cultivation) and November 2003 (after one year cultivation) at Site 1, 80 surface soil samples from 0 to x cm depth were collected at 10 m intervals to investigate the spatial variations of pH and electric conductivity (EC). The pH and EC were determined in a ane : 5 soil to water ratio. To evaluate the salinization and sodication of soils in this site, soil profiles of approximately 1 m in depth were investigated on November 2002 and November 2004. Soil profiles of approximately 1 g in depth were also examined in Sites 2, iii, 4, and v on November 2002. Soil samples were collected for laboratory assay of the soil physicochemical properties.

Soil samples were air-stale, crushed, and passed through a 2-mm sieve. Soil properties known to be influenced by the accumulation of salts and/or those affecting the optical properties of the soil were determined for each prepared sample by standard laboratory methods. These properties were soil particle size distribution, pH, EC, wet content, soluble salt content, Olsen P, total C, total N, and available micronutrients. Particle size distribution was measured using the pipette method [12] later on removal of carbonate salts with 1 Chiliad CH₃COONa (pH 5) [13]. Soil texture triangle and distribution percentage measurements were used to define the soil texture of the samples. The ECe was determined from soil saturated water extract using air-dried soil and distilled water. The amount of cations (Ca²⁺, Mg^two+, K⁺, and Na⁺) and anions (SO₄ ²⁻, NO_iii ⁻, and Cl⁻) present in each of the irrigation water and soil samples were measured using an diminutive absorption spectrophotometer (Hitachi, Z-2300) and ion chromatography (Shimadzu, LC-10A). The HCO₃ ⁻ (alkalinity) was measured by titration. An Olsen P test was carried out by shaking five g of air-dried soil in 100 mL of 0.5 M-NaHCO₃ (pH viii.five) for thirty minutes in an end-over-terminate shaker [fourteen], and so measuring the P concentration in the solution using spectrophotometric method. Total C and Northward levels were determined by dry out combustion using a SumiGraph NCH-21 analyzer (Sumika, MT 700). Available manganese (Mn_d), iron (Iron_d), copper (Cu_d), and zinc (Zn_d) were extracted with diethylenetriamine penta-acetic acid (DTPA-PAC) [15] and quantified with ICP (Rigaku, CIROS CCD). The clay mineralogy was adamant by X-ray diffraction (Rigaku, RINT2500HF) using Mg- and Chiliad-saturated clay. In addition, rut (350°C, 550°C) and glycerol treatments were performed.

three. Results and Word

3.i. Backdrop of the Irrigation Water in the Investigated Expanse

The quantity of well h2o that could be obtained for irrigation in the investigated area varied from farm to subcontract. It depended largely on the financial status of each individual farmer, because information technology costs the farmer to pump up water from wells. The properties of irrigation water used in the investigated areas are shown in Table ii. The US Salinity Laboratory's diagram [16] is used widely for classifying irrigation water. According to the diagram, the water samples were classified as C3S1, indicating a high salinity and low sodium take a chance. However, loftier concentrations of bicarbonate ion were also observed in the water samples, which tin can effect in loftier soil pH and may cause deficiencies in iron or other micronutrients [17].

Sites	pH	EC dS m−1	Cations and anions (mmolc L−1)								SAR (mmol 50)ane/two
			Ca2+	Mg2+	Thou+	Na+				Cl−
Site i	vii.99	0.96	4.10	ii.16	0.09	3.47	0.93	0.58	2.63	iv.69	1.96
Site 2	8.02	0.83	2.66	one.94	0.22	four.eighty	0.87	0.01	2.33	v.76	3.17
Site 3	seven.78	1.38	half dozen.06	4.26	0.45	five.11	ane.24	0.39	2.12	11.11	two.25
Site 4	vii.81	one.74	7.32	5.04	0.63	9.86	one.50	0.00	2.06	15.lxx	3.97
Site 5	vii.81	one.74	7.32	v.04	0.63	9.86	1.fifty	0.00	2.06	15.70	iii.97

three.2. Morphological Properties and Salt Status of Soils

Pedon descriptions for the soil profiles obtained from the investigated areas are summarized in Table 3. The morphological and physicochemical properties of the soil profiles are shown in Table 4. Here, nosotros described the soil and irrigation backdrop of each site.

Soil Depth (cm) Boundary Structure Compactness Roots Horizon Dis. Con. Site 1; Later on tillage of fulijol beans Ap1 0–18 Clear Smooth SG Very loose VF-f, F-f Ap2 18–28 Clear Smooth SG Very loose VF-f, F-f C1 28–fifty/58 Difuse Wavy SG Loose VF-f C2 50/58–105 Clear Smoothen SG Loose VF-f C3 105–115+ SG Loose None Site 2; Under cultivation of chille guerito Ap 0–16 Clear Shine SG Very loose VF-yard, F-f C1 sixteen–40 Difuse Smooth SG Medium VF-f C2 40–65/71 Articulate Wavy SG Loose VF-f C3 65/71–75+ SG Loose None Site iii; Under cultivation of chille guerito Ap 0–22 Difuse Smooth SBK-F-W, GR-F-Westward Very loose VF-chiliad, F-f C1 22–45 Difuse Smooth SBK-F-W, SBK-G-W Loose VF-co C2 45–65 Difuse Smooth SBK-F-W, SBK-M-Due west Loose VF-co C3 65–75+ MA Loose VF-f Site four-one; Nether cultivation of chille guerito Ap1 0–10 Clear Smooth SBK-Thou-W, GR-F-W Very loose VF-f Ap2 10–22 Abrupt Shine SBK-Grand-Mo, SBK-C-Mo Very loose VF-f Bw 22–35 Clear Wavy SBK-G-Mo, ABK-G-Mo, ABK-M-S Medium None Bk 35–46/49 Clear Wavy ABK-M-Mo Compact None Bkm 46/49–60+ ABK-M-S Very compact None Site 4-ii; Under cultivation of fulijol beans Ap1 0–10 Clear Smooth SBK-F-Due west, SBK-Grand-W Very loose VF-f Ap2 10–20/25 Abrupt Wavy SBK-F-W Very loose VF-f Bk 20/25–39/41 Difuse Wavy SBK-C-W Loose None BC 39/41–66/71 Articulate Wavy SBK-M-W Medium None Bkm 66/71–75+ MA Very meaty None Site 5; Nether cultivation of chille guerito Ap 0–17/32 Sharp Wavy SBK-M-W, GR-F-Westward Loose VF-co Bk1 17/32–55 Difuse Smoothen MA Very compact None Bk2 55–threescore+ MA Very compact None

aPurlieus—Dis.: distinctnesss, Con.: configuration. Construction: type-size grade—type: GR: granular, MA: massive, ABK: angular blocky, SBK: subangular blocky, SG: single grain.—size: F: fine, 1000: medium, C: fibroid.—grade: W: weak, Mo: moderate, S: strong. roots, size quantity—size: CO: coarse, F: fine, G: medium, VC: very fibroid, VF: very fine. quantity—f: few, c: common, m: many.

		Particle size distribution (%)							The amount of soluble salts in saturated extract (cmolc kg)
Soil Horizon	Depth (cm)	Coarse sand	Fine sand	Silt	Clay	Soil Texure	pH	EC dS m	Cations				Anions				SAR (mmol L
									Ca2+	Mg2+	Chiliad+	Na+				Cl
Site one-1; No cultivation (before application of diluted sulfuric acid)—November, 2002
A1	0–x	73.42	22.58	2.91	1.09	South	8.17	0.49	0.07	0.03	0.04	0.04	0.01	0.00	0.19	0.02	1.07
A2	10–twenty	53.72	39.51	3.38	iii.39	Southward	eight.04	0.57	0.08	0.03	0.03	0.07	0.02	0.00	0.15	0.05	one.78
C11	20–30	57.66	36.02	ii.21	4.11	S	8.05	0.80	0.13	0.05	0.02	0.05	0.01	0.01	0.20	0.10	1.00
C12	30–40	66.44	26.66	4.63	2.27	S	8.10	0.61	0.03	0.11	0.02	0.04	0.01	0.00	0.13	0.05	0.90
C21	40–50	68.98	25.30	3.50	2.22	S	8.14	0.68	0.15	0.04	0.01	0.05	0.01	0.01	0.16	0.06	0.97
C22	50–60	65.09	30.33	3.55	1.03	Due south	8.02	0.54	0.02	0.09	0.01	0.06	0.01	0.02	0.15	0.04	1.52
C31	threescore–fourscore	73.54	22.85	3.eleven	0.fifty	S	8.05	0.42	0.06	0.01	0.01	0.04	0.01	0.02	0.08	0.02	one.26
C32	fourscore–90	65.36	29.82	three.28	one.54	Due south	seven.ninety	0.32	0.04	0.01	0.01	0.03	0.01	0.01	0.06	0.01	one.fourteen
C41	90–105	69.82	26.26	2.85	1.07	S	7.98	0.35	0.01	0.06	0.01	0.05	0.01	0.01	0.13	0.02	1.59
C42	105–115+	70.16	24.82	3.98	1.04	S	7.94	0.31	0.04	0.01	0.01	0.03	0.01	0.00	0.06	0.01	1.xiv
Site 1-2; Subsequently tillage of fulijol beans (afterward application of diluted sulfuric acid))—Nov, 2004
Ap11	0–x	60.62	32.17	four.67	2.54	South	seven.93	0.lxx	0.06	0.03	0.03	0.xi	0.02	0.00	0.05	0.sixteen	3.09
Ap12	10–18	57.07	35.85	4.02	3.06	S	eight.08	0.48	0.06	0.03	0.03	0.05	0.01	0.00	0.04	0.11	1.32
Ap2	18–28	60.68	33.42	3.73	2.17	Due south	8.00	0.69	0.05	0.02	0.02	0.13	0.03	0.00	0.03	0.18	3.85
C11	28–37	76.fifteen	19.58	two.47	1.lxxx	Due south	vii.78	0.83	0.08	0.04	0.02	0.13	0.03	0.00	0.02	0.20	3.26
C12	37–50/58	62.71	32.60	ii.99	1.lxx	Due south	five.23	0.77	0.07	0.04	0.01	0.eleven	0.02	0.00	0.00	0.nineteen	2.69
C21	50/58–62	66.10	30.43	2.70	0.77	S	4.67	0.56	0.04	0.03	0.01	0.09	0.01	0.00	0.00	0.14	2.91
C22	62–80	58.87	37.11	2.47	ane.55	South	v.32	0.37	0.02	0.02	0.01	0.07	0.01	0.00	0.00	0.08	2.91
C23	fourscore–105	82.96	15.37	one.39	0.28	South	5.00	0.27	0.01	0.01	0.01	0.05	0.01	0.00	0.00	0.05	3.fifteen
C3	105–115+	79.63	17.45	1.36	1.56	South	7.03	0.18	0.01	0.01	0.01	0.04	0.00	0.00	0.01	0.03	2.15
Site 2; Under cultivation of chille guerito—November, 2002
Ap1	0–8	20.94	61.06	8.88	nine.12	SL	7.89	2.51	0.32	0.eighteen	0.05	0.36	0.17	0.19	0.04	0.46	4.21
Ap2	8–sixteen	xx.18	61.41	nine.56	eight.85	SL	seven.86	1.29	0.16	0.08	0.04	0.xx	0.04	0.11	0.04	0.17	3.23
C11	16–29	21.25	59.39	9.82	9.54	SL	7.61	1.08	0.12	0.05	0.05	0.15	0.03	0.sixteen	0.02	0.08	3.08
C12	29–40	24.eighty	53.10	10.46	11.64	SL	7.58	0.72	0.08	0.03	0.03	0.11	0.03	0.ten	0.02	0.08	2.65
C21	twoscore–55	26.99	49.74	x.31	12.96	SL	7.68	0.66	0.08	0.03	0.02	0.10	0.02	0.07	0.02	0.08	2.44
C22	55–65/71	24.74	51.eleven	9.72	xiv.43	SL	7.79	0.68	0.09	0.04	0.01	0.xi	0.03	0.06	0.03	0.09	two.38
C3	65/71–75+	23.74	51.81	xi.21	13.24	SL	eight.17	0.66	0.09	0.03	0.01	0.ten	0.03	0.02	0.06	0.11	2.48
Site iii; Under cultivation of chille guerito—November, 2002
Ap1	0–10	20.99	53.62	9.93	15.46	SCL	vii.45	3.13	0.62	0.36	0.04	0.23	0.09	0.94	0.02	0.18	1.76
Ap2	x–22	20.73	53.86	9.09	16.32	SCL	7.89	2.30	0.44	0.24	0.02	0.23	0.14	0.51	0.06	0.15	ii.09
C11	22–33	18.95	52.40	ten.09	xviii.56	SCL	seven.93	0.99	0.16	0.09	0.02	0.12	0.05	0.08	0.05	0.21	1.77
C12	33–45	18.93	fifty.25	xi.41	19.41	SCL	7.81	0.83	0.13	0.07	0.02	0.15	0.04	0.04	0.04	0.22	2.46
C21	45–55	24.thirty	46.20	10.74	18.76	SCL	vii.69	0.87	0.13	0.07	0.01	0.xiii	0.04	0.03	0.03	0.22	two.28
C22	55–65	30.29	41.45	ten.55	17.71	SCL	seven.84	0.79	0.13	0.06	0.01	0.14	0.04	0.01	0.03	0.22	2.48
C3	65–75+	38.40	37.75	8.18	15.67	SCL	7.64	0.89	0.12	0.06	0.01	0.12	0.04	0.01	0.02	0.21	two.35
Site 4-1; Nether cultivation of chille guerito—November, 2002
Ap1	0–x	3.30	xl.68	25.84	xxx.18	LiC	8.10	5.25	0.70	0.64	0.15	ii.36	0.65	0.37	0.17	ii.31	11.87
Ap2	10–22	3.01	43.87	25.57	27.55	LiC	8.45	2.93	0.09	0.08	0.07	1.44	0.xviii	0.51	0.22	0.59	22.03
Bw	22–35	two.79	35.92	25.72	35.57	LiC	8.15	ix.45	0.60	0.68	0.24	half-dozen.49	2.18	0.20	0.14	5.09	31.23
Bk	35–46/49	i.84	36.28	25.97	35.91	LiC	7.56	42.00	3.94	vii.55	0.52	25.03	two.27	0.37	0.11	27.xc	41.49
Bkm	46/49–threescore+	ii.12	35.48	25.25	37.fifteen	LiC	7.68	30.fifty	1.ninety	iv.fourteen	0.71	nineteen.94	2.03	0.00	0.10	nineteen.81	44.x
Site 4-2; Under tillage of fulijol beans—November, 2002
Ap1	0–10	5.83	45.45	21.97	26.75	LiC	vii.99	18.15	two.31	0.54	0.37	11.91	four.43	0.36	0.13	9.03	40.89
Ap2	10–twenty/25	5.47	46.50	22.02	26.01	LiC	8.16	3.97	0.97	0.18	0.10	i.86	one.77	0.26	0.15	0.48	10.49
Bk	twenty/25–39/41	ii.63	41.11	22.96	33.30	LiC	8.22	11.93	1.71	0.25	0.35	10.36	10.76	0.00	0.12	i.30	39.57
BC	39/41–66/71	three.04	42.53	24.65	29.78	LiC	7.93	39.60	0.49	0.22	0.59	27.72	five.27	0.00	0.xiii	21.eighteen	192.69
Bkm	66/71–75+	2.03	70.87	15.83	11.27	SCL	vii.48	66.xc	0.50	0.35	0.68	35.48	ii.28	0.00	0.05	31.02	268.18
Site 5; Under cultivation of chille guerito—November, 2002
Ap1	0–5	9.86	9.09	27.40	53.65	HC	8.xv	4.32	0.56	0.twoscore	0.24	1.80	0.16	0.63	0.thirteen	1.69	10.seventy
Ap2	5–17/32	10.35	ix.34	27.51	52.80	HC	8.58	1.81	0.14	0.09	0.10	0.81	0.09	0.36	0.21	0.31	9.78
Bk11	17/32–35	12.93	8.62	23.56	54.89	HC	8.71	1.xxx	0.05	0.03	0.04	0.66	0.07	0.00	0.21	0.44	14.01
Bk12	35–55	7.05	8.98	25.97	58.00	HC	8.38	6.97	0.thirty	0.45	0.24	5.07	i.06	0.00	0.23	iv.26	29.53
Bk2	55–60+	half-dozen.07	8.86	25.91	59.16	HC	8.25	10.fifty	0.44	0.80	0.28	vii.95	1.04	0.00	0.20	vii.29	36.23

Site 1. 12 mm irrigation water was applied every hour from baste irrigation tube holes at this site. In full, 36 mm of irrigation water was applied to the field every three days. The changes in spatial variations of the salt aggregating condition (EC_1 : 5) and pH_1 : five in surface soil from November 2002 to November 2003 are shown in Figure 2. Salts in the soil were redistributed by irrigation and the soil pH_ane : 5 increased with the utilize of the drip irrigation over this one yr period. Though the increase in soil EC_one : 5 was slight, the increment in soil pH_1 : 5 was remarkable. Because the clay content was low, the soil showed high water permeability. The salt composition of this soil could hands have been changed when salts were leached with irrigation water that contained sodium carbonates. This resulted in the high soil alkalinity, observed [xvi]. Although soil ECe (electrical conductivity of a saturated paste extract) was depression, soil pHe (pH of a saturated paste excerpt), alkalinity and SAR (sodium adsorption ratio) levels were high. The relative high pHe and low ECe have been due to the fact that the amount of water is controlled and, therefore, limited, while under conventional irrigation, salts and fertilizers were leached out due to the low water retention of the sandy-textured soils. Though salt aggregating in the soil was not observed, soil alkalinity was heightened. A meaning corporeality of the sodium carbonate in the irrigation water was transferred to the soil, thereby increasing its soil content. Taking the event as mentioned above, the quantity of irrigation water was reduced to 12 mm every three days, and a moderate corporeality of diluted sulphuric acid was applied with the baste irrigation. Diluted sulphuric acid was prepared by dilution of sulphuric acid (91%, 34.14 mol L^−one) by 5000 times. We added the diluted sulphuric acrid solution to the drip irrigation liquid fertilizer used for drip irrigation at the first of irrigation. While ECe and pHe was maintained in the surface soil, the subsoil pHe decreased (meet Tabular array four). Crop production was maintained in spite of a reduction in the quantity of irrigation water. This suggests that it is possible to use just one third the amount of irrigation h2o typically to this site.

Site 2. Plant growth in Site two was poor compared with that in Site one. The soil profile of Site ii showed neither evolution of soil structure nor differentiation of soil horizon. The ploughed layer was approximately 20 cm thick, and a hardpan layer was observed at a depth of 20 to twoscore cm. The root growth of plants was limited past this hardpan layer. 3-iv mm irrigation water was applied every hour from the drip irrigation tube holes at this site. In other words, 9–12 mm of irrigation h2o was practical to the field every three days. The subsurface was moist, which indicates excessive irrigation. The susceptibility of the soil to salinization was depression, because its sandy texture ensured high h2o permeability; furthermore, the quality of the irrigation water was comparatively high. Crop growth was poor considering root zones were limited to the top surface of the soil, and plants could not absorb the fertilizer that passed through the hard subsurface pan.

Site 3. The plant growth at Site 3 was good compared with that of Sites 1 and ii. 3-4 mm irrigation h2o was practical every hour past drip irrigation at this site. In other words, 36–48 mm of irrigation water was practical to the field every three days. The soil at this site contained a very soft till lower layer, the event of deep ploughing. Roots were observed fifty-fifty in this lower layer. The soil had a sandy texture, and soil salinization was not observed despite excessive irrigation with lower quality water. Plants grew well at this site, because the root zone was wide, assuasive more than efficient absorbance of nutrients. However, we fright that underground water may become polluted by nitrate leaching, caused past the excessive application of fertilizer and excessive irrigation.

Site 4. At Site 4, virtually of the salts were accumulated not only in the surface only besides in the whole soil profile due to excessive long-term irrigation. three-four mm irrigation water was practical every hour past drip irrigation. In other words, 9–12 mm of irrigation h2o was practical to the field every ten to xv days by drip irrigation. This field showed well-defined areas with potent institute growth and other areas with poor establish growth. Surficial atmospheric precipitation of white was observed in areas where plant growth was poor. This field was not well leveled, and salinization of surface soil was observed at the concave areas. The permeability of the soil was very low, causing a large amount of salt accumulation at a depth of xxx cm below the surface. The salts added by irrigation accumulated at the uneven parts of the soil surface, and water moved gradually to the low layer of the soil profile. Evaporation then caused salts to precipitate at the surface of the soil in these lower parts, resulting in the simultaneous accumulation of salts and salinization and sodication of these lower areas. In addition, concretion of calcium carbonate was increased in the soil layers below 50 cm in the soil profile. The root zone was limited to the ploughed layer, which was i of the causes of poor constitute growth. Both plant root growth and h2o percolation were completely prevented by soil compaction, which triggered farther salinization and sodication of the soil.

Site five. The plant growth at Site 5 was as poor as in Site 4. The soil was dry and very hard from the subsurface to the lower layers. Plant roots were but extending into the ploughed layer (0–17 to 32 cm). Between 2-3 mm of water was discharged every 60 minutes, resulting in a charge per unit of irrigation of 10–15 mm every five to six days. Though salt did not accumulate on the surface of the soil, the pHe level was loftier. Root-like mottling of calcium carbonate was observed in the lower layer of the soil profile. The irrigation water increased the salt concentration and, therefore, the risk of long-term salinization of this field. All the same, the corporeality of irrigation water applied was just a quarter of that used at Site i. At least once per year, heavy rains caused the fields at this site to flood and remain saturated for several days. The natural flooding of this field appeared to protect the state from soil salinization. Flooding leads to the leaching of salts into lower layers and increases the soil pHe. In other words, the sodium salts were leached, and the overall salt composition was changed by irrigation and rain. Hardpan was formed in the clayey soil every bit a result of the low table salt concentration and high pHe.
The salt dynamics of the profiles of the irrigated soils differed from site to site even in sites that were most 1 another. It is, therefore, best to consider efficient management methods on a site by site to maximize crop yields using a minimal input of water and fertilizer.

3.3. Assay of Bachelor Micronutrients in Soils

The available micronutrients in the soils of the investigated areas are shown in Table 5. Total C and total N contents, as well every bit soil bachelor , were low in all soil profiles. The aggregating of organic textile was also low throughout all the soils of the investigated area. The fertility of these soils was very depression because of the arid atmospheric condition, which wearisome the decomposition rate of organic matter. Total Due north and total C content in dirt soils were slightly higher than that in sandy soils farms. The clay soil layers under 50 cm in the profile were rich in total carbon because of the pregnant amount of concretions of calcium carbonate. Moreover, table salt accumulated soils showed a tendency to decrease the quantity of available phosphorus; This may result from the formation of insoluble phosphorus complexes.

Soil	Depth (cm)	T-C (one thousand kg−1)	T-N (g kg−1)	Available P (mg kg−i)	Bachelor micronutrients (mg kg−1)
Horizon					Mn	Fe	Cu	Zn
Site 1-1; no cultivation (before application of diluted sulfuric acid)
A1	0–10	1.fifteen	0.75	0.08	2.81	2.52	0.22	0.22
A2	10–20	i.04	0.66	0.06	two.08	2.32	0.21	0.15
C11	xx–thirty	0.92	0.33	0.08	2.54	2.88	0.19	0.12
C12	thirty–twoscore	0.55	0.25	0.12	3.65	2.l	0.18	0.12
C21	xl–l	0.56	0.31	0.11	iii.22	2.03	0.28	0.14
C22	50–60	0.58	0.28	0.15	3.54	ane.98	0.21	0.21
C31	60–80	0.56	0.27	0.13	2.95	1.84	0.18	0.xviii
C32	80–90	0.52	0.22	0.17	ii.44	2.32	0.nineteen	0.13
C41	90–105	0.55	0.28	0.15	two.69	2.eleven	0.21	0.12
C42	105–115+	0.53	0.26	0.17	2.36	1.88	0.19	0.xiv
Site ane-2; later cultivation of fulijol beans (after awarding of diluted sulfuric acid)
Ap11	0–x	2.42	0.89	0.03	two.76	2.54	0.19	0.22
Ap12	10–18	2.62	0.87	0.04	ii.37	2.29	0.17	0.twenty
Ap2	xviii–28	2.74	0.87	0.06	2.29	2.82	0.16	0.20
C11	28–37	one.73	0.77	0.xi	2.73	four.07	0.sixteen	0.19
C12	37–50/58	i.65	0.70	0.57	x.56	thirteen.57	0.24	0.20
C21	50/58–62	ane.28	0.47	0.37	10.36	16.ninety	0.28	0.16
C22	62–80	0.91	0.48	0.38	9.ninety	11.12	0.27	0.14
C23	80–105	0.81	0.29	0.27	7.20	9.25	0.24	0.thirteen
C3	105–115+	0.58	0.37	0.12	3.11	3.06	0.18	0.10
Site 2; under cultivation of chille guerito
Ap1	0–8	ii.23	0.64	0.28	nine.21	3.48	0.46	0.31
Ap2	8–16	2.49	0.50	0.31	10.03	4.05	0.50	0.28
C11	sixteen–29	2.00	0.53	0.36	5.nineteen	3.38	0.42	0.22
C12	29–40	one.70	0.47	0.27	7.12	2.95	0.fifty	0.19
C21	twoscore–55	1.99	0.85	0.31	7.56	2.43	0.52	0.15
C22	55–65/71	1.84	0.88	0.17	8.32	i.86	0.55	0.14
C3	65/71–75+	1.81	0.81	0.38	vi.84	1.80	0.50	0.14
Site three; nether cultivation of chille guerito
Ap1	0–10	three.02	0.95	0.twenty	17.49	2.38	0.83	0.22
Ap2	ten–22	3.12	i.22	0.17	8.37	2.11	0.77	0.17
C11	22–33	2.09	0.78	0.18	vii.02	2.l	0.61	0.10
C12	33–45	i.75	0.79	0.21	seven.20	iii.nineteen	0.61	0.x
C21	45–55	i.70	0.84	0.eighteen	seven.77	3.73	0.66	0.09
C22	55–65	1.50	0.95	0.xix	8.42	3.65	0.63	0.07
C3	65–75+	1.45	0.75	0.16	eight.46	3.17	0.62	0.09
Site iv-1; under cultivation of chille guerito
Ap1	0–10	six.60	1.34	0.64	eleven.78	2.xiv	1.22	0.30
Ap2	ten–22	seven.10	i.55	1.06	13.08	2.31	ane.22	0.32
Bw	22–35	6.52	ane.27	1.20	seven.50	2.76	ane.28	0.19
Bk	35–46/49	xi.32	0.88	0.94	v.92	ane.76	0.91	0.17
Bkm	46/49–threescore+	fifteen.21	0.97	0.55	4.61	1.85	0.80	0.16
Site 4-two; under cultivation of fulijol beans
Ap1	0–10	eleven.84	i.17	1.58	6.38	2.xiii	ane.04	0.27
Ap2	10–twenty/25	11.03	ane.23	one.54	half dozen.95	2.81	1.12	0.18
Bk	20/25–39/41	fifteen.96	0.72	0.68	2.23	one.71	0.72	0.xi
BC	39/41–66/71	11.04	i.06	0.57	three.26	0.99	0.49	0.12
Bkm	66/71–75+	ix.87	0.79	0.85	3.20	0.56	0.38	0.09
Site 5; under cultivation of chille guerito
Ap1	0–5	15.19	1.85	2.56	7.xi	three.58	one.56	0.18
Ap2	5–17/32	17.46	2.84	2.36	5.66	three.55	1.57	0.22
Bk11	17/32–35	12.xxx	i.51	ane.09	8.58	3.84	1.64	0.19
Bk12	35–55	11.91	ane.12	1.01	10.88	three.67	ane.79	0.15
Bk2	55–threescore+	eleven.64	1.19	i.28	10.35	3.29	i.70	0.15

Few available micronutrients were observed in the analyzed soil profiles, with the exception of those at Site ane, which had sandy soils and depression pHe. Micronutrients were available in the post-obit guild: Mn_d > Fe_d > Cu_d > Zn_d > Cd_d in all soil layers, except for those at Site 1, where the Cu_d content was low in all layers and Fe_d > Mn_d in the lower layers of the soil profile. The Cu_d content was proportional to the dirt content (Figure iii). In addition, soil layers with low pHe tend to have increased Fe_d content. Information technology has been suggested that exchangeable Cu in clay was solubilised, and Fe was solubilised at depression soil pHe (Figure 4). A high and negative correlation () was observed between the ratio of Mn_d/TAM (total amount of available micronutrients; Mn_d + Fe_d + Cu_d + Zn_d + Cd_d) and the ratio of Fe_d/TAM in the ratio of each bachelor micronutrient for TAM (Figure five). Furthermore, a high and negative correlation () between (Mn_d + Fe_d)/TAM and Cu_d/TAM was observed (Figure vi).

(a)

(b)

iii.iv. Clay Mineral Compositions in Soils

The main mineral and clay mineral composition of selected soil layers are shown in Tabular array 6. K-feldspar, plagioclase, biotite, and quartz were observed as the primary mineral components in all sampled sites. Illite and quartz, a pocket-sized amount of vermiculite, smectite, and kaolinite were besides observed. It was suggested that the effect of weathering are reduced by the large amount of K-feldspars in the fine sand fractions, besides equally the illite and the modest amounts of kaolinite in the clay fraction. However, the degree of weathering at Site i was a little higher, considering a large corporeality of 2 : one type dirt minerals and kaolinite were observed at this site. It appears that the process of soil germination at Site 1 may have been somewhat unlike that at the other sites. That is, changes from biotite to kaolinite and from biotite to vermiculite and/or smectite in the clay mineral limerick at Site one occurred at the outset phase of weathering. The diversity of the primary mineral composition ratio is thought to have been caused by heavy pelting and flooding that occurs several times each twelvemonth.

Qtz Bi Kfs Pl Cal Kln Ill Sm Vt Site ane  Surface soil + + ++++ ++++ tr + ++ + +  Subsoil +++ tr ++ ++ tr + ++ + + Site 2  Surface soil +++ + ++ ++ tr tr ++ tr tr  Subsoil +++ + + + tr tr ++ tr tr Site 3  Surface soil +++ + ++ ++ tr tr ++ tr tr  Subsoil +++ + + + tr tr ++ tr tr Site 4  Surface soil +++ + +++ +++ tr tr ++ tr tr  Subsoil +++ + ++++ ++++ tr tr ++ tr tr Site five  Surface soil ++++ + + + tr tr ++ tr tr  Subsoil ++++ + + + tr tr +++ tr tr

Qtz: quartz; Bi: biotite; Kfs: K-feldspar; Pl: plagioclase; Cal: calcite; Kln: kaolinite; Ill: illite; Sm: smectite; Vt: vermiculite; tr: trace mineral phase.

3.5. Soil Management Based on Soil Properties

Soil salinization and sodication are complexly interrelated with many factors such as soil characteristics, amount and composition of salts in the soil, the quantity and quality of irrigation water, and the method of irrigation used. Preventive measures must, therefore, be established against soil deposition, including matching the prevalent soils with suitable crops. A reduction in the application of irrigation water and fertilizer is necessary to forbid soil salinization. Sustainable long-term crop production requires appropriate soil and water management strategies that are specific to the prevalent field atmospheric condition. It is important to prevent both the depletion of available h2o resource and the degradation of soils past salinization. A reduction in the leaching of fertilizer will also minimize hush-hush water pollution. A reduction of water usage tin can improve crop growth and prevent the salinization and/or sodication of the soil. Moreover, in that location is a need to accept into business relationship the present state of water resources and irrigation efficiency.

iv. Decision

The salt and water dynamics observed in the soil profiles of irrigated farmlands in southern Baja California are profoundly influenced past the prevalent soil characteristics. It is important to understand the distribution and the current land of soil resources and to take soil and water conservation into consideration when developing sustainable agriculture strategies. This report detailed some of the soil backdrop of the area, which may provide insight into methods of irrigation management and the specific research needs of different barren soils.

Acknowledgment

The authors highly capeesh and acknowledge the Japan Society for the Promotion of Science (JSPS) for supporting this study through the Cadre University Program and the Global COE Program.

Copyright

Copyright © 2011 Tsuneyoshi Endo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in whatever medium, provided the original piece of work is properly cited.

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Source: https://www.hindawi.com/journals/aess/2011/873625/

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