Quang San, Ninh Son, Ninh Thuan
Dat xam nau d Quang San, Ninh San d miic chua it den rat chua (hinh 4), PHHOH dao dong tir 5.53 - 8.08, trung binh 6.48; pH^a tir 3.94 - 6.46, trung binh PHHOH dao dong tir 5.53 - 8.08, trung binh 6.48; pH^a tir 3.94 - 6.46, trung binh 4.94, chenh lech giira pHnoH ^^ PHRCI tir 1.12 - 1.62, cho thay do chua tiem tang eiia dat kha cao. MSu NS-24 la dat trdng liia 3 vu, mau NS-26 va NS-31 la dat trdng mia + san, vdi cac dieu kien canh tac khong tdt la nguyen nhan ca ban gia tang do chua ciia dat. Mau NS-28 la dat chua sir dung, chua cd sir tac dong dang ke ciia boat dong nhan tac, lam tang tinh dem ciia dat nen dat it chua, cd pH nude d miic kiem yeu la di su cd mat dang ke ciia cac cation kim loai kiem va
ki^m thd d dieu kien it bi rira troi. MSu NS-22 va NS-29 la dat trdng mia va dieu luan canh, da't duac bdn them vdi nen it chua han.
pH 10
D pHH20 • pHKCI
NP-01 NP-03 NP-04 NP-05 NP-06 NP-07 NP-08 NP-10 NP-12 Mau
Hinh 5. Do chua cua dat xam nau vung ban khd han huyen Ninh Phude
Da't xam nau d cac xa Nhi Ha, Phude San, Phude Vinh, huyen Ninh Phude, Ninh Thuan d miJc chua vira den trung tinh (hinh 5), pHnoH dao dong tir
5.24 - 8.83, trung binh 6.85; pHj^ci ^^ 3.81 - 7.46, gia tri chenh lech giira do chua hien tai va do chua tiem tang d miic kha cao, tir 0.69 - 1.74. Cac mau NP-01 la
da't trdng xoai,NP-05 la dat ddng ed, NP-12 la dat trdng nho deu cd dieu kien canh tac tdt nen do chua ciia da't d miic trung tinh, la dieu kien thuan Igi cho cay phat trien. Cac mSu dat khac deu lay tai cac vudn trdng ngo, nho va tao. Tai mlu NP-04 va NP-10 la dat trdng ngo, deu chua ban cac dat khac la do trong qua trinh canh tac cd sir dung nhieu phan hda hoc bdn cho cay trdng, ddng thdi ngudi dan khong quan tam den viec bdn them vdi va phan huu ca cho dat.
Tren ca sd nhung ket qua dieu tra, khao sat thuc dia ket hgp vdi cac ket qua nghien cuu cho thay do chua trong dat rat khac nhau tai cac dia ban nghien cull. Dieu nay d^ dang giai thieh ve cac nguyen nhan anh hudng den do chua cua cac dat tren. Yeu td quan trgng nhat anh hudng den do chua la do qua trinh phong hda da hinh thanh dat va cac dieu kien canh tac. Cac mSu dat ciia huyen Ninh San deu d dieu kien dia hinh cao va ddc ban huyen Ninh Phude nen cd qua